1. Field of the Invention
The present invention relates to a disk drive device for rotating a disk.
2. Description of the Related Art
Disk drive devices, such as hard disk drives, have become miniaturized. The capacity of a disk drive device has also been increased. Such disk drive devices have been installed in various types of electronic devices. In particular, such disk drive devices have been installed in portable electronic devices such as cellular phones or portable music players. With regard to disk drive devices that are installed in portable electronic devices, their impact resistance has been required to be improved so that the disk drive devices can withstand impacts, such as those due to dropping, compared with the case of stationary electronic devices such as personal computers.
On the other hand, in general, portable electronic devices have been required to be made thinner, smaller, and lighter. Therefore, disk drive devices that are installed in portable electronic devices have also been required to be made thinner, smaller, and lighter. However, it is possible that the impact resistance decreases in the course of making the disk drive devices thinner, smaller, and lighter. It can be said that there is a trade-off imposed on the disk drive devices that are installed in portable electronic devices.
For example, in the case where the disk drive device is used for a desk-top PC, any impact applied to the disk drive device would be small, and it would not be likely that the disk drive device malfunctions in normal usage. However, in the case where the disk drive device is used for portable electronic devices, the disk drive device may receive a large impact such as those due to dropping. There would be many cases where a large impact is applied to the disk drive device. Therefore, there is a possibility that the disk drive device malfunctions in normal usage unless the disk drive device has considerable impact resistance.
In order to cope with this, the prior art installs a fluid dynamic bearing unit (hereinafter referred to as “FDB”) in a disk drive device as disclosed in Japanese Patent Application Publication No. 2007-198555. In this FDB, a flange portion is sandwiched between an extended portion of a sleeve and the end surface of a housing. The flange portion is formed in an inner cylindrical region. A lubricant is filled in between the flange portion and the extended portion of the sleeve, and the lubricant is also filled in between the flange portion and the end surface of the housing.